Multiple pipette and method of using the same

ABSTRACT

A multiple pipette (X) comprising a first pipette ( 1 ) and a second pipette ( 2 ), wherein the first pipette ( 1 ) allows a liquid stored in a liquid storing section ( 17   a ) to be delivered a plurality of times by a fixed amount each and the second pipette ( 2 ) allows a liquid drawn in from outside to be delivered all at a time. The first pipette ( 1 ) is designed to deliver a liquid a plurality of times by a fixed amount each, e.g., by utilizing a ratchet mechanism ( 12   d,    13   a ). The first pipette ( 1 ) preferably has a cap ( 19 ) removably attached to the front end thereof.

TECHNICAL FIELD

The present invention relates to a multiple pipette having a pluralityof pipettes and a method of using the same. Such multiple pipettesinclude ones for dispensing plural kinds of liquids separately andothers for mixing plural kinds of liquids or diluting a target liquidfor dispensing the mixed liquid or the diluted liquid.

BACKGROUND ART

For measuring the concentration of a particular component in a sampleliquid, there exists a method in which the sample liquid containing anunknown concentration of the particular component and a reference liquidcontaining a known concentration of the particular component are bridgedfor measuring a potential difference generated therebetween to therebycompute the concentration of the particular component from the measuredpotential difference.

In this method, a concentration measuring plate is set, for example, toan analyzing apparatus for determining the concentration of theparticular component.

The analyzing apparatus includes at least a set section for setting theplate, two probes, and computation means for computing the concentrationof the particular component from the potential difference between theprobes.

The plate includes at least a first liquid receiving portion to which areference liquid is applied, a first terminal for conduction with thereference liquid applied to the first liquid receiving portion, a secondliquid receiving portion to which a sample liquid is applied, a secondterminal for conduction with the sample liquid applied to the secondliquid receiving portion, and a bridge for shorting between thereference liquid in the first liquid receiving portion and the sampleliquid in the second liquid receiving portion.

When the plate is set to the set section of the analyzing apparatus, theprobes of the analyzing apparatus come into contact with the firstterminal and the second terminal for measuring the potential differencebetween the reference liquid and the sample liquid. The computationmeans computes the concentration of the particular component of thesample liquid based on the measured potential difference.

A double pipette may be used for applying the reference liquid to thefirst liquid receiving portion and for applying the sample liquid to thesecond liquid receiving portion of the plate. For example, use maybemade of such a double pipette that includes a first pipette for drawingand dispensing the reference liquid through a liquid dispensing orificeand a second pipette for drawing and dispensing the sample liquidthrough a liquid dispensing orifice. The first pipette and the secondpipette are held in a casing for example so that the distance betweenrespective liquid dispensing orifices corresponds to the distancebetween the first liquid receiving portion and the second liquidreceiving portion of the plate. The liquid dispensing orifice of eachpipette may be an opening of a tip attached to the tip end of thepipette.

The double pipette may have the following problems when the referenceliquid previously drawn in remains in the tip. Firstly, the amount ofdispensing fluctuates when the remaining reference liquid is dispensedtogether with the reference liquid later drawn in. Such fluctuation ofthe dispensing amount also occurs when the first pipette cannot draw aliquid by a constant amount. Secondly, when the drawing and dispensingof a reference liquid is performed after a long interval from theprevious drawing and dispensing of the reference liquid, the referenceliquid remaining in the tip as adhered to the inner surfaceconcentrates. The mixing of the concentrated liquid into the latersucked reference liquid causes the concentration of the reference liquidto vary.

When a sample liquid previously drawn in remains in the tip, thefollowing problems may occur. Since the concentrations of a particularcomponent may differ between the sample liquids to be measured, when theremaining sample liquid is mixed in a sample liquid to be measured next,the concentration of the sample liquid may vary.

Therefore, in the prior art double pipette, the tip of each pipette isreplaced every time the reference liquid or the sample liquid isdispensed for avoiding the influence of the reference liquid or sampleliquid previously drawn in and dispensed. However, this causes thefollowing problems.

Firstly, since a large number of tips need be used, the pipette isdisadvantageous in terms of the cost. The number of tips disposed of (aswaste) is correspondingly large. Secondly, although the same referenceliquid is used for plural measurements, the reference liquid need bedrawn in each time of the measurements. Therefore, the drawing work istroublesome when a large number of sample liquids need be measured.Moreover, even when a tip is replaced every time of the drawing anddispensing of the liquid, the problem of the sucking amount fluctuationis not solved. Therefore, it is still impossible to dispense the liquidby a fixed amount.

DISCLOSURE OF THE INVENTION

According to a first aspect of the present invention, there is provideda multiple pipette which includes a first pipette for dispensing aliquid stored in a liquid storing section divisionally a plurality oftimes each by a constant amount, and a second pipette for dispensing aliquid drawn from the outside all at a time.

In a preferred embodiment, the first pipette includes a piston rod forpushing out the liquid from the liquid storing section, and a cylinderaccommodating the piston rod at least partially. The piston rod isformed with a plurality of successive ratchet grooves, whereas thecylinder is provided with a pawl for engagement with the plurality ofratchet grooves. The cylinder is movable in a first direction togetherwith the piston rod with the pawl engaged in the ratchet groove and ismovable in a second direction opposite the first direction separatelyfrom the piston rod.

In a preferred embodiment, the piston rod is provided with an operationknob, which is movable for moving the piston rod separately from thecylinder. Moving the operation knob in the first direction causes a gasin the liquid storing section to be discharged, whereas moving theoperation knob in the second direction causes a liquid to be drawn intothe liquid storing section.

In a preferred embodiment, the first pipette incorporates a slide piecefor supporting the pawl. The pawl is held on the slide piece when thepiston rod is moved by the operation knob.

In a preferred embodiment, the first pipette includes a piston rod forpushing out the liquid from the liquid storing section, and a housingaccommodating the piston rod. The liquid storing section is defined by asyringe having an inner space, and the syringe is threadedly attached tothe housing.

In a preferred embodiment, the first pipette includes a nozzle connectedto the liquid storing section. The nozzle includes a dispensing orificefor dispensing the liquid in the liquid storing section to the outside.

The first pipette may include a cap removably attached for covering thedispensing orifice. The nozzle may be protected by a reinforcingportion.

According to a second aspect of the present invention, there is provideda method of using a multiple pipette which comprises a first pipette fordispensing a first liquid stored in a liquid storing sectiondivisionally a plurality of times each by a constant amount, and asecond pipette for dispensing a second liquid drawn from the outside allat a time. The first liquid may be a reference liquid containing a knownconcentration of a particular component, whereas the second liquid maybe a sample liquid containing an unknown concentration of a particularcomponent.

According to a third aspect of the present invention, there is provideda multiple pipette which comprises a first pipette for dispensing afirst liquid stored in a liquid storing section divisionally a pluralityof times each by a constant amount, and a second pipette for dispensinga second liquid drawn from the outside all at a time. The first liquidmay be mixed with the second liquid or the second liquid may be dilutedwith the first liquid.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view illustrating an example of multiple pipetteaccording to the present invention.

FIG. 2 is an enlarged view illustrating a principal part of the firstpipette constituting the multiple pipette of FIG. 1.

FIG. 3 is an exploded perspective view illustrating a potentialdifference measuring plate.

FIG. 4 is an enlarged view of a principal portion in a state where areference liquid and a sample liquid are applied to the potentialdifference measuring plate of FIG. 3 using the multiple pipette of FIG.1.

BEST MODE FOR CARRYING OUT THE INVENTION

As shown in FIG. 1, a multiple pipette X includes a first pipette 1 anda second pipette 2. The first pipette 1 and the second pipette 2 areheld in a casing 3.

The first pipette 1 includes a housing 10, a piston rod 11 and acylinder 12. The piston rod 11 is held in the housing 1 with the upperend portion thereof received in the cylinder 12.

The piston rod 11 has a rod section 13 and a plug 14. The rod section 13has an upper end portion to which an operation knob 13 c is attached viaan outwardly projecting pin 13 b. As clearly shown in FIG. 2, the rodsection 13 has a mid-portion formed with a plurality of successiveratchet grooves 13 a.

As shown in FIG. 1, the cylinder 21 is formed, at the upper end portionthereof, with an engagement portion 12 a which is larger in diameterthan other portions. The cylinder 12 has a circumferential wall 12 bformed with a slit 12 c. The slit 12 c extends longitudinally of thecylinder 12 for allowing the vertical movement of the pin 13 b. Thecircumferential wall 12 b has a lower end portion to which a pawl 12 dis pivotally attached. As clearly shown in FIG. 2, the pawl 12 d is inthe form of a crank. The tip end of the pawl 12 d is configuredcorrespondingly to the configuration of the ratchet grooves 3 a. Thoughnot clearly shown in the figure, the pawl 12 d is biased toward thepiston rod 11 by a torsion coil spring for example. Therefore, when thepawl 12 d moves downward, the pawl 12 d engages the ratchet groove 13 a,thereby moving the piston rod 11 downward together. On the other hand,when the pawl 12 d moves upward, the pawl 12 d does not engage theratchet groove 13 a so that the pawl 12 d moves separately from thepiston rod 11.

As shown in FIG. 1, the housing 10 has an upper opening 10 a and a loweropening 10 b.

A rod section 15 a of a push rod 15 is inserted in the upper opening 10a. The push rod 15 has a plug 15 b accommodated in the housing 10 inclose contact with the upper surface of the cylinder 12. The rod section15 a has an upper end to which an operating portion 15 c is attached. Anengagement portion 10 e is provided in the housing 10. A coil spring 16is disposed between the engagement portion 10 e and the engagementportion 12 a of the cylinder 12. The coil spring 16 surrounds the upperend portion of the cylinder 12. Thus, the cylinder 12 and the push rod15 are biased in the upward direction in FIG. 1.

A syringe 17 is threadedly fitted into the lower opening 10 b of thehousing 10. The syringe 17 includes a liquid storing section 17 a towhich a nozzle 17 b is threadedly fitted. Thus, the syringe 17 isremovable from the housing 10. The liquid storing section 17 a isremovable from the syringe 17. When removed, the liquid storing section17 a can be easily washed.

The nozzle 17 b is in the form of a thin tube at portions except for theportion threadedly fitted to the liquid storing section 17 a, so that aliquid retained in the liquid storing section 17 a can be directlydispensed from the nozzle 17 b. Therefore, the first pipette 1 does notrequire the use of tips. Therefore, the number of tips used by themultiple pipette can be reduced, which leads to reduction in cost andwaste.

The tubular portion of the nozzle 17 b is protected by a reinforcingportion 17 c except for the tip end of the nozzle. A cap 19 for coveringthe tip end of the nozzle 17 b is removably attached to the reinforcingportion 17 c. Preferably, the cap 19 is attached so that the tip end ofthe nozzle 17 c is held in close contact with the inner bottom surfaceof the cap.

The nozzle 17 b is likely to be bent because of its thin tubularconfiguration. However, the provision of the reinforcing portion 17 cprevents the nozzle 17 b from being damaged. Further, the cap 19 can beeasily attached owing to the provision of the reinforcing portion.

The attaching of the cap 19 to the nozzle 17 b prevents the evaporationof the liquid retained in the liquid storing section 17 a. Therefore, itis possible to prevent a particular component from concentrating due tothe evaporation of water for example, so that the concentration of theliquid to be dispensed is kept unchanged for a long time.

As clearly shown in FIG. 2, a slide piece 18 is provided in the housing10. The slide piece 18 is provided over the ratchet grooves 13 a. In anormal state, the pawl 12 d is held on the slide piece 18. While thepawl 12 d moves downward for a distance corresponding to the width (thedimension in the vertical direction of FIG. 1) of the slide piece 18,the pawl 12 d moves on the slide piece 18. When the pawl 12 d movesdownward for a distance exceeding the width of the slide piece, the pawl12 d drops from the slide piece 18 into engagement with the ratchetgroove 13 a. As described above, when the pawl 12 d moves downward inthe engaged state, the piston rod 11 d moves downward together with thepawl 12 d. When the pawl 12 d moves upward, the pawl 12 d moves asseparated from the piston rod 11.

The housing 10 has a side wall 10 c formed with a window 10 d forallowing the vertical movement of the pin 13 b. The plug 14 of thepiston rod 11 is arranged in the liquid storing section 17 b as closelyfitted therein. Thus, when the pawl 12 d is held on the slide piece 18,the vertical movement of the operation knob 13 c makes the piston rod 11move vertically within the housing 10 and the liquid storing section 17b.

In the first pipette 1, liquid is retained in the liquid storing section17 a in the following manner.

First, with the cap 19 removed, the operation knob 13 c is moveddownward to lower the piston rod 11, thereby discharging the gas fromthe liquid storing section 17 a. Subsequently, with the operation knob13 c kept lowered, the tip end of the nozzle 17 b is placed in liquid tobe drawn. Then, the operation knob 13 c is moved upward to raise thepiston rod 11, thereby drawing the liquid into the liquid storingsection 17 a.

The liquid in the liquid storing section 17 a is dispensed as follows.First, the operating portion 15 c of the push rod 15 is moved downwardto lower the cylinder 12 and the pawl 12 d. As clearly shown in FIG. 2,since the pawl 12 d is held on the slide piece 18 in the normal state,the pawl 12 d moves downward on the slide piece 18 in accordance withthe downward movement of the push rod 15. When the pawl 12 d is furthermoved downward, the pawl 12 d drops from the slide piece 18 intoengagement with the ratchet groove 13 a. When the push rod 15 is furtherlowered, the piston rod 11 moves downward together with the pawl 12 d.As a result, the liquid in the liquid storing section 17 a is pusheddownward for dispensing from the tip end of the nozzle 17 b by an amountin accordance with the amount of movement of the piston rod 11.

For dispensing a constant amount of liquid in each time of theoperation, the stroke of the piston rod 11 in each time of the operationneeds to be fixed. For this purpose, the stroke of the piston rod 11 isset equal to one pitch of the ratchet grooves 13 a or to an integralmultiple of one pitch. Accordingly, the stroke of the push rod 15 is thevalue obtained by adding the one pitch or an integral multiple of theone pitch of the ratchet grooves 13 a to the movement distance of thepawl from the state held on the slide piece 18 until it comes intoengagement with the ratchet groove 13 a.

When the force applied to the operating portion 15 c is released afterthe dispensing of liquid from the first pipette 1, the cylinder 12, thepush rod 15 and the pawl 12 d move upward due to the biasing force ofthe coil spring 16. At this time, the pawl 12 d disengages from theratchet groove 13 a and moves upward again on the slide piece 18 to beheld at its original position.

With the multiple pipette X, repeating of the operation of lowering thepiston rod 11 by the exertion of a force to the operating portion 15 cand then releasing the force enables repetitive dispensing of the liquidby a constant amount. Therefore, fluctuations of dispensing amount ofliquid due to fluctuations of drawing amount of liquid can be avoided.

The second pipette 2 includes a housing 20, a piston rod 21 and anintermediate rod 22. The piston rod 21 and the intermediate rod 22 areaccommodated in the housing 20.

The housing 20 includes a housing body 20A and a nozzle section 20B. Thenozzle section is formed with a tip end opening 20 a which providescommunication between the inside and outside of the housing 20. Thehousing body 20A is formed, at the lower position and the middleposition thereof, with engagement portions 20 b, 20 b projectinginwardly toward the center.

The piston rod 21 includes a rod section 21 a and a plug 21. The plug 21is accommodated in the housing body 20A. The rod section 21 a isaccommodated partially in the housing body 20A and partially in thenozzle section 20B. A coil spring 24 is disposed between the plug 21 band the engagement portion 20 b of the housing body 20A. The coil spring24 surrounds the upper end portion of the rod section 21 a. The coilspring 24 biases the piston rod 21 in the upper direction in FIG. 1.

The intermediate rod 22 includes a rod section 22 a and a plug 22 b. Theplug 22 b is held in close contact with the plug 21 b of the piston rod21. Therefore, the intermediate rod 22 is also biased in the upperdirection in FIG. 1.

The housing 22 has an upper surface formed with an opening 20 a. A rodsection 23 a of a push rod 23 is inserted in the opening 20 a. The pushrod 23 is provided with a plug 23 b, which is accommodated in thehousing 20 as kept in close contact with the upper end of theintermediate rod 22. The rod section 23 a has an upper end to which anoperating portion 23 c is attached. A coil spring 25 is disposed betweenthe lower surface of the plug 23 b and the engagement portion 20 c ofthe housing body 20A. The coil spring 25 surrounds an upper portion ofthe intermediate rod 22. The coil spring 25 biases the pushing rod 23upward.

With the second pipette 2, the drawing and dispensing of liquid isperformed as follows.

First, a tip 26 is attached to the tip end of the nozzle section 20B.Subsequently, a force is exerted to the operating portion 23 c of thepush rod 23 to move the piston rod 21 and the intermediate rod 22downward. Then, with the tip 26 placed in a sample liquid contained in avial or a test tube, the force exerted to the push rod 23 is released.As a result, the piston rod 21, the intermediate rod 22 and the push rod23 biased by the springs 24, 25 move upward to draw the liquid into thetip 26. For example, 20 μl of sample liquid is drawn.

The dispensing of the liquid is performed by moving the push rod 23downward to push out the liquid from the tip 26. When the force appliedto the push rod 23 is released, the push rod 23 returns to its originalstate due to the biasing force of the coil springs 24, 25.

The multiple pipette X is capable of dispensing two kinds of liquid. Forexample, a reference liquid containing a known concentration and asample liquid containing an unknown concentration may be dispensed.Therefore, as shown in FIG. 4, the multiple pipette X may be used forsimultaneously supplying a reference liquid and a sample liquid to apotential difference measuring plate 4 as shown in FIG. 3.

The potential difference measuring plate 4 is used for measuring apotential difference between a reference liquid and a sample liquid withan analyzing apparatus (not shown). In the analyzing apparatus, theconcentration of a particular component of the sample liquid is computedin accordance with the measured potential difference.

As clearly shown in FIG. 3, the potential difference measuring plate 4includes a base film layer 40 on which a resist layer 41 and a coverfilm layer 42 are laminated. The potential difference measuring plate 4measures the potential difference with respect to three kinds of ionssuch as Na⁺, Ka⁺ and Cl⁻, for example.

The base film layer 40 has insulating properties. The base film layer 40has an elongated rectangular configuration as a whole.

The base film layer 40 has an opposite pair of end edges respectivelyformed with three terminals 40A-40C and three terminals 40D-40F. Thethree terminals 40A-40C, 40D-40F are aligned widthwise of the base filmlayer 40. As will be described later, each of the terminals 40A-40F isbrought into contact with a probe for measuring the potentialdifference.

The base film layer 40 is centrally formed with six liquid receivingpads 40 a-40 f. The liquid receiving pads 40 a-40 f are provided forreceiving particular components of reference liquid or sample liquid.The liquid receiving pads 40 a-40 f are electrically connected to theterminals 40A-40F via conductive wires 40Aa, 40Bb, 40Cc, 40Dd, 40Ee and40Ff, respectively.

The resist film layer 41 comprises a first resist film layer 43 and asecond resist film layer 44. The first resist film layer 43 and thesecond resist film layer 44 have insulating properties. Each of thefirst resist film layer 43 and the second resist film layer 44 has anelongated rectangular configuration as a whole.

The resist film 41 has an opposite pair of end edges respectively formedwith three insertion holes 41A-41C and three insertion holes 41D-41F.The insertion holes 41A-41F are provided at locations corresponding tothe terminals 40A-40F of the base film layer 40. Each of the insertionholes 41A-41F is made up of a corresponding one of through-holes 43A-43Fformed in the first resist film layer 43 and a corresponding one ofthrough-holes 44A-44F formed in the second resist film layer 44. Theterminals 40A-40F are exposed through the through-holes 41A-41F,respectively.

The second resist film layer 44 is centrally formed with sixcommunication holes 44 a-44 f. The communication holes 44 a-44 f arerespectively provided with ion selection membranes 45 a-45 f fittedtherein. For example, the ion selection membranes 45 a, 45 d selectivelypass Na⁺, the ion selection membranes 45 b, 45 e selectively pass K⁺,and the ion selection membranes 45 c, 45 f selectively pass Cl⁻.

The first resist film 43 is centrally formed with a reference liquidretaining opening 43 g and a sample liquid retaining opening 43 h. Thereference liquid retaining opening 43 g communicates with the threecommunication holes 44 a, 44 b, 44 c. The sample liquid retainingopening 43 h communicates with the three communication holes 44 d, 44 e,44 f. The reference liquid retaining opening 43 g communicates with thereference liquid retaining opening 43 h through a cutout 43 i. A bridge45 i for allowing the movement of ions is disposed in the cutout 43 i.

The cover film layer 42 has an opposite pair of end edges respectivelyformed with three insertion holes 42A-42C and three insertion holes42D-42F. The insertion holes 42A-42F communicate with the insertionholes 41A-41F of the resist film layer 41, respectively. Therefore, theterminals 40A-40F of the base film layer 40 are exposed through therelevant insertion holes 41A-41F.

The cover film layer 42 has an opposite pair of longitudinal edges whichare centrally formed with a reference liquid receiving hole 42 g and asample liquid receiving hole 42 h, respectively. The reference liquidreceiving hole 42 g communicates with the reference liquid retainingopening 43 g of the first resist film layer 43. The sample liquidreceiving hole 42 h communicates with the sample liquid retainingopening 43 h of the first resist film layer 43. The cover film layer 42is further formed with insertion holes 42B, 42E and two air vents 42 jprovided adjacent to the insertion openings. Each of the air vents 42 jcommunicates with both the reference liquid retaining opening 43 g andthe sample liquid retaining opening 43 h.

For applying a reference liquid R and a sample liquid S to the potentialdifference measuring plate 4, the tip end of the nozzle 17 b of thefirst pipette 1 is positioned at the reference liquid receiving hole 42g, whereas the tip end of the tip 26 attached to the second pipette 2 ispositioned at the sample liquid receiving hole 42 h. Then, respectiveoperating portions 15 c, 23 c of the push rods 15, 23 of the pipettes 1,2 are moved downward. As a result, a predetermined amount of referenceliquid R is dispensed from the first pipette 1 and the reference liquidR is applied to the plate through the reference liquid receiving hole 42g. Form the second pipette 2, a predetermined amount of sample liquid Sis dispensed and applied to the plate through the sample liquidreceiving hole 42 h.

The reference liquid applied through the reference liquid receiving hole42 g is retained in the reference liquid retaining opening 43 g, whereasthe sample liquid S applied through the sample liquid receiving hole 42h is retained in the sample liquid retaining opening 43 h. Since thereference liquid retaining opening 43 g is connected to the sampleliquid receiving hole 42 h via the cutout 43 i provided with the bridge45 i, the reference liquid R and the sample liquid S areshort-circuited.

The Na⁺, Ka⁺, Cl⁻ ions in the reference liquid R retained in thereference liquid retaining opening 43 g pass through the relevant ionselection membranes 45 a, 45 b, 45 c to reach the reference liquidreceiving pads 40 a, 40 b, 40 c. The Na⁺, Ka⁺, Cl⁺ ions in the sampleliquid S retained in the sample liquid retaining opening 43 h passthrough the relevant ion selection membranes 45 d, 45 e, 45 f to reachthe sample liquid receiving pads 40 d, 40 e, 40 f. As a result,potential differences are generated between the reference liquidreceiving pads 40 a, 40 b, 40 c and the sample liquid receiving pads 40d, 40 e, 40 f, respectively, due to the concentration difference of Na⁺,Ka⁺ or Cl⁻ between the reference liquid R and the sample liquid S.

The potential differences are measured by potential differencemeasurement means (not shown) having six probes P₁-P₆. The potentialdifference due to the Na⁺concentration difference is measured bybringing probes P₁, P₂ into contact with the terminals 40A, 40D. Thepotential difference due to the K⁺ concentration difference is measuredby bringing probes P₃, P₄ into contact with the terminals 40B, 40E. Thepotential difference due to the Cl⁻ concentration difference is measuredby bringing probes P₅, P₆ into contact with the terminals 40C, 40F.

The concentration of each ion can be determined from the measuredpotential based on a calibration curve prepared in advance, for example.

With the multiple pipette X, the reference liquid R in the liquidstoring section 17 a can be dispensed as divided into a plurality oftimes each by a constant amount. Therefore, even in the case where theconcentration measurement of a particular component is performed withrespect to a plurality of sample liquids S, the drawing of the referenceliquid R into the first pipette 1 need not be performed for each sampleliquid R to be measured. The attachment and removal of the tip 26relative to the first pipette 1 is also unnecessary. Therefore, theoperation efficiency in applying the reference liquid R and the sampleliquid S is enhanced. Since the first pipette 1 does not require tips,the total number of tips used by the multiple pipette X decreases, whichleads to the reduction in cost and amount of the resulting waste.

In the multiple pipette according to the present invention, when theamount of liquid in the liquid storing section becomes insufficient, theliquid storing section may be replaced with another one containingsufficient reference liquid.

The multiple pipette according to the present invention may be used formixing plural kinds of liquids or diluting a target liquid. In thiscase, respective liquid dispensing orifices of the first and the secondpipettes may be made close to each other or combined with each other formixing or diluting the liquids.

The multiple pipette according to the present invention may includethree or more pipettes.

1. A multiple pipette comprising: a first pipette for dispensing a firstliquid stored in a liquid storing section divisionally a plurality oftimes each by a constant amount; and a second pipette for dispensing asecond liquid drawn from outside all at a time; wherein the firstpipette includes a first housing, a first push rod for the divisionaldispensing of the first liquid and an operating member for causing thefirst liquid to be drawn into the liquid storing section: wherein thesecond pipette includes a second housing, and a second push rod for thedispensing of the second liquid; wherein the first housing and thesecond housing are accommodated together in an overall casing; whereinthe first push rod and the operating member extend out beyond the firsthousing and the overall casing; and wherein the second push rod extendsout beyond the second housing and the overall casing.
 2. The multiplepipette according to claim 1, wherein the first pipette includes apiston rod for pushing our the liquid from the liquid storing sectionand a cylinder accommodating the piston rod at least partially andconnected to the first push rod; the piston rod being formed with aplurality of successive ratchet grooves; the cylinder being providedwith a pawl for engagement with the plurality of ratchet grooves; thecylinder being movable in a first direction together with the piston rodwith the pawl engaged in the ratchet groove and movable in a seconddirection opposite the first direction separately from the piston rod.3. The multiple pipette according to claim 2, wherein the piston rod isconnected to the operation member which is movable for moving the pistonrod separately from the cylinder; and the operation member being movedin the first direction for causing a gas in the first liquid storingsection to be discharged, the operation member being moved in the seconddirection for causing the first liquid to be drawn into the liquidstoring section.
 4. The multiple pipette according to claim 3, whereinthe first pipette incorporates a slide piece for supporting the pawl,the pawl being held on the slide piece when the piston rod is moved bythe operation member.
 5. The multiple pipette according to claim 1,wherein the first pipette includes a piston rod accommodated in thefirst housing for pushing out the liquid from the liquid storingsection; the liquid storing section being defined by a syringe having aninner space, the syringe being threadedly attached to the first housing.6. The multiple pipette according to claim 1, wherein the first pipetteincludes a nozzle connected to the liquid storing section, the nozzleincluding a dispensing orifice for dispensing the liquid from the liquidstoring section to the outside.
 7. The multiple pipette according toclaim 6, wherein the first pipette includes a cap removably attached forcovering the dispensing orifice.
 8. The multiple pipette according toclaim 6, wherein the nozzle is protected by a reinforcing portion.
 9. Amultiple pipette comprising: a first pipette for dispensing a liquidstored in a liquid storing section divisionally a plurality of timeseach by a constant amount; and a second pipette for dispensing a liquiddrawn front outside all at a time; wherein the first pipette includes apiston rod for pushing out the liquid from the liquid storing section,and a cylinder accommodating the piston rod at least partially; thepiston rod being formed with a plurality of successive ratchet grooves;the cylinder being provided with a pawl for engagement with theplurality of ratchet grooves; the cylinder being movable in a firstdirection together with the piston rod with the pawl engaged in theratchet groove and movable in a second direction opposite the firstdirection separately from the piston rod.
 10. The multiple pipetteaccording to claim 9, wherein the piston rod is provided with anoperation knob which is movable for moving the piston rod separatelyfrom the cylinder; and the operation knob being moved in the firstdirection for causing a gas in the liquid storing section to bedischarged, the operation knob being moved in the second direction forcausing a liquid to be drawn into the liquid storing section.
 11. Themultiple pipette according to claim 10, wherein the first pipetteincorporates a slide piece for supporting the pawl the pawl being heldon the slide piece when the piston rod is moved by the operation knob.